The invention relates to machine tools in general, and more particularly to improvements in apparatus for supplying coolant to material removing stations in machine tools, for example, to the locations of contact between a workpiece and a grinding wheel in a grinding machine.
It is known to equip a grinding machine with a nozzle which can discharge one or more jets, sprays or streams of a suitable liquid coolant to the location of contact between a workpiece and a material removing tool, such as a rotary grinding wheel. The nozzle can be trained or aimed upon the location of contact and is connectable to a source of coolant, e.g., by a hose. Such cooling of the location of contact between a workpiece and a grinding tool is not only desirable but actually necessary for the quality of the finished product, especially in a modern grinding machine wherein the tool is expected to remove large quantities of material from a stationary or movably mounted workpiece. Adequate cooling prevents localized overheating of workpieces and thus enhances the quality of the finished products.
It is further known to design a nozzle in such a way that it can supply adequate quantities of coolant in suitable distribution to the location of contact between a large (wide) surface of a workpiece and a suitably profiled (wide) working surface of a rotary grinding wheel or an analogous tool. The nozzle can satisfy the requirements regarding the delivery of adequate quantities of coolant in optimum distribution only as long as the corresponding grinding tool remains installed in the machine and as long as such tool is in the process of removing material from a particular series of workpieces. If the grinding tool is replaced with another tool, or if another profile of the same tool is moved into material removing contact with a workpiece, the nozzle does no longer ensure optimal withdrawal of heat from workpieces. Thus, it is necessary to replace the nozzle with a different nozzle in a time-consuming operation which entails long periods of idleness of the machine. The situation is aggravated if several different profiles of a particular workpiece are to be treated by a set of different tools or by two or more sets of different tools. This necessitates the removal of a previously used grinding tool from the machine. The same applies if the grinding machine is equipped with a manipulator which is capable of automatically exchanging a previously used grinding tool with a different tool during the interval between two successive different treatments of a workpiece in a grinding machine.
It is further known to guide a coolant discharging nozzle in a grinding machine in such a way that the nozzle remains trained upon the location of contact between a workpiece and a grinding tool, even if the position of such location varies in the course of a grinding operation, i.e., the stream or streams of coolant can be caused to follow or track the location of material removal from a workpiece to thus avoid fluctuations in the rate of withdrawal of heat from the workpiece. Reference may be had, for example, to German Pat. No. 39 30 247 Al which discloses a centerless circular grinding machine wherein the orientation of the coolant discharging nozzle varies in dependency on the extent of a reduction of the diameter of the grinding wheel as a result of dressing of the working surface of the grinding wheel in actual use. The intensity of the material removing action of the dressing tool upon the working surface of the grinding wheel is monitored and the orientation of the nozzle which discharges coolant against the workpiece is adjusted accordingly.
German Pat. No. 34 22 213 Al discloses a coolant supplying apparatus which employs nozzles in a distribution such that their orientation partially conforms to the profile of the grinding wheel. The nozzles are mounted for translatory movement on a pivotally mounted protective hood. This enables the nozzles to trail or track, to a certain extent, the location of contact between a workpiece and a grinding wheel. However, the patented apparatus cannot take into consideration the differences between the profile of a previously utilized grinding wheel and the profile of a second grinding wheel which is installed in the grinding machine upon removal of the previously used wheel.